Image display devices such as autostereoscopic screens are used to present 3D images so that they can be perceived three-dimensionally without special spectacles. A particular class of such screens, the class of the so-called “light field displays”, is characterized by a specific geometry. With these screens, a period of the grating arranged in front of the matrix screen provided in the lateral direction corresponds to an integer multiple (whole number multiple) of a spacing of adjacent columns of the matrix screen, said grating deflecting light emanating from the pixels into different laterally mutually offset sectors. Such a screen has been described e.g. by H. Hoshino, F. Okano, H. Isono and I. Yuyama in J. Opt. Soc. Am. A 15, 2059, 1998.
The columns of such a matrix screen can be distributed in a cyclic order onto a number of channels corresponding to the whole number ratio between the column spacing and the grating period. Due to the specific geometry, the light emanating from the matrix screen is then directed or restricted by the grating so that light emanating from the pixels of each of these channels forms rays or light beams directed in parallel behind the grating. An appropriate use of the screen now provides that each of these channels is controlled using image information of precisely one view from a plurality of views which correspond to parallel projections of a scene from slightly deviating directions. Exactly one of these views is then displayed on the pixels of each of these channels. In a viewing space in front of the screen, a light field thereby arises in which a viewer of the screen can move and with both eyes sees two images which result in each case as a mixture of different ones of the parallel projected views. These images then correspond to two centrally projected images which complement one another as stereoscopic half-images to form a stereoscopic image so that the viewer perceives the scene three-dimensionally, and indeed from a direction dependent on his position.
In this manner, however, only comparatively small depths of field can be realistically displayed. A further disadvantage can be seen in that a significantly large amount of image information is required which can only be acquired with a large computation effort or with very complex taking processes, namely the image information of a plurality of parallel projections of the scene to be displayed.